EDC3 phosphorylation regulates growth and invasion through controlling P‐body formation and dynamics

Regulation of mRNA stability and translation plays a critical role in determining protein abundance within cells. Processing bodies (P‐bodies) are critical regulators of these processes. Here, we report that the Pim1 and 3 protein kinases bind to the P‐body protein enhancer of mRNA decapping 3 (EDC3) and phosphorylate EDC3 on serine (S)161, thereby modifying P‐body assembly. EDC3 phosphorylation is highly elevated in many tumor types, is reduced upon treatment of cells with kinase inhibitors, and blocks the localization of EDC3 to P‐bodies. Prostate cancer cells harboring an EDC3 S161A mutation show markedly decreased growth, migration, and invasion in tissue culture and in xenograft models. Consistent with these phenotypic changes, the expression of integrin β1 and α6 mRNA and protein is reduced in these mutated cells. These results demonstrate that EDC3 phosphorylation regulates multiple cancer‐relevant functions and suggest that modulation of P‐body activity may represent a new paradigm for cancer treatment.     

On the role of tannin vacuoles in several nastic leaf responses

Summary Experiments were done to relate the presence of tannin vacuoles to plant movements. When surveyed, 4 out of 10 species exhibited rapid thigmonastic or nyctinastic movements, and only those 4 species had tannin vacuoles in their motor cells. Interestingly, plants ofAlbizzia julibrissin whose seed was obtained in New Haven, Connecticut had rapid nyctinasty and tannin vacuoles in the tertiary pulvini, whereasAlbizzia collected in Winston-Salem, North Carolina had neither. Nyctinasty ofMimosa pudica andAlbizzia NH, both of which had tannin vacuoles, was at the rate of 4.2 °/min, whereasAlbizzia WS andSamanea saman, neither of which had tannin vacuoles, exhibited leaflet closure at the rate of 2.0–2. 1 °/min. Pretreatment with the Ca²⁺ channel agonist Bay K-8644 increased, and with the antagonist verapamil decreased, the rate of leaflet closure only inMimosa andAlbizzia NH. Pretreatment with the Ca²⁺ inhibitor Erythrosin B substantially blocked reopening only inMimosa andAlbizzia NH. We conclude that tannin vacuoles assist nastic movements to be rapid by acting as a store of Ca²⁺ and releasing it as a second messenger upon mechanical perturbation or darkness.Abbreviations FR far-red irradiation - MP mechanical perturbation - TV tannin vacuoles